drivers/cpufreq/cpufreq_ondemand.c

   1 /*
   2  *  drivers/cpufreq/cpufreq_ondemand.c
   3  *
   4  *  Copyright (C)  2001 Russell King
   5  *            (C)  2003 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>.
   6  *                      Jun Nakajima <jun.nakajima@intel.com>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  */
  12
  13 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  14
  15 #include <linux/cpufreq.h>
  16 #include <linux/init.h>
  17 #include <linux/kernel.h>
  18 #include <linux/kernel_stat.h>
  19 #include <linux/kobject.h>
  20 #include <linux/module.h>
  21 #include <linux/mutex.h>
  22 #include <linux/percpu-defs.h>
  23 #include <linux/slab.h>
  24 #include <linux/sysfs.h>
  25 #include <linux/tick.h>
  26 #include <linux/types.h>
  27 #include <linux/cpu.h>
  28
  29 #include "cpufreq_governor.h"
  30
  31 /* On-demand governor macros */
  32 #define DEF_FREQUENCY_DOWN_DIFFERENTIAL         (10)
  33 #define DEF_FREQUENCY_UP_THRESHOLD              (80)
  34 #define DEF_SAMPLING_DOWN_FACTOR                (1)
  35 #define MAX_SAMPLING_DOWN_FACTOR                (100000)
  36 #define MICRO_FREQUENCY_DOWN_DIFFERENTIAL       (3)
  37 #define MICRO_FREQUENCY_UP_THRESHOLD            (95)
  38 #define MICRO_FREQUENCY_MIN_SAMPLE_RATE         (10000)
  39 #define MIN_FREQUENCY_UP_THRESHOLD              (11)
  40 #define MAX_FREQUENCY_UP_THRESHOLD              (100)
  41
  42 static DEFINE_PER_CPU(struct od_cpu_dbs_info_s, od_cpu_dbs_info);
  43
  44 static struct od_ops od_ops;
  45
  46 #ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND
  47 static struct cpufreq_governor cpufreq_gov_ondemand;
  48 #endif
  49
  50 static unsigned int default_powersave_bias;
  51
  52 static void ondemand_powersave_bias_init_cpu(int cpu)
  53 {
  54         struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info, cpu);
  55
  56         dbs_info->freq_table = cpufreq_frequency_get_table(cpu);
  57         dbs_info->freq_lo = 0;
  58 }
  59
  60 /*
  61  * Not all CPUs want IO time to be accounted as busy; this depends on how
  62  * efficient idling at a higher frequency/voltage is.
  63  * Pavel Machek says this is not so for various generations of AMD and old
  64  * Intel systems.
  65  * Mike Chan (android.com) claims this is also not true for ARM.
  66  * Because of this, whitelist specific known (series) of CPUs by default, and
  67  * leave all others up to the user.
  68  */
  69 static int should_io_be_busy(void)
  70 {
  71 #if defined(CONFIG_X86)
  72         /*
  73          * For Intel, Core 2 (model 15) and later have an efficient idle.
  74          */
  75         if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL &&
  76                         boot_cpu_data.x86 == 6 &&
  77                         boot_cpu_data.x86_model >= 15)
  78                 return 1;
  79 #endif
  80         return 0;
  81 }
  82
  83 /*
  84  * Find right freq to be set now with powersave_bias on.
  85  * Returns the freq_hi to be used right now and will set freq_hi_jiffies,
  86  * freq_lo, and freq_lo_jiffies in percpu area for averaging freqs.
  87  */
  88 static unsigned int generic_powersave_bias_target(struct cpufreq_policy *policy,
  89                 unsigned int freq_next, unsigned int relation)
  90 {
  91         unsigned int freq_req, freq_reduc, freq_avg;
  92         unsigned int freq_hi, freq_lo;
  93         unsigned int index = 0;
  94         unsigned int jiffies_total, jiffies_hi, jiffies_lo;
  95         struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info,
  96                                                    policy->cpu);
  97         struct dbs_data *dbs_data = policy->governor_data;
  98         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
  99
 100         if (!dbs_info->freq_table) {
 101                 dbs_info->freq_lo = 0;
 102                 dbs_info->freq_lo_jiffies = 0;
 103                 return freq_next;
 104         }
 105
 106         cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_next,
 107                         relation, &index);
 108         freq_req = dbs_info->freq_table[index].frequency;
 109         freq_reduc = freq_req * od_tuners->powersave_bias / 1000;
 110         freq_avg = freq_req - freq_reduc;
 111
 112         /* Find freq bounds for freq_avg in freq_table */
 113         index = 0;
 114         cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_avg,
 115                         CPUFREQ_RELATION_H, &index);
 116         freq_lo = dbs_info->freq_table[index].frequency;
 117         index = 0;
 118         cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_avg,
 119                         CPUFREQ_RELATION_L, &index);
 120         freq_hi = dbs_info->freq_table[index].frequency;
 121
 122         /* Find out how long we have to be in hi and lo freqs */
 123         if (freq_hi == freq_lo) {
 124                 dbs_info->freq_lo = 0;
 125                 dbs_info->freq_lo_jiffies = 0;
 126                 return freq_lo;
 127         }
 128         jiffies_total = usecs_to_jiffies(od_tuners->sampling_rate);
 129         jiffies_hi = (freq_avg - freq_lo) * jiffies_total;
 130         jiffies_hi += ((freq_hi - freq_lo) / 2);
 131         jiffies_hi /= (freq_hi - freq_lo);
 132         jiffies_lo = jiffies_total - jiffies_hi;
 133         dbs_info->freq_lo = freq_lo;
 134         dbs_info->freq_lo_jiffies = jiffies_lo;
 135         dbs_info->freq_hi_jiffies = jiffies_hi;
 136         return freq_hi;
 137 }
 138
 139 static void ondemand_powersave_bias_init(void)
 140 {
 141         int i;
 142         for_each_online_cpu(i) {
 143                 ondemand_powersave_bias_init_cpu(i);
 144         }
 145 }
 146
 147 static void dbs_freq_increase(struct cpufreq_policy *p, unsigned int freq)
 148 {
 149         struct dbs_data *dbs_data = p->governor_data;
 150         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 151
 152         if (od_tuners->powersave_bias)
 153                 freq = od_ops.powersave_bias_target(p, freq,
 154                                 CPUFREQ_RELATION_H);
 155         else if (p->cur == p->max)
 156                 return;
 157
 158         __cpufreq_driver_target(p, freq, od_tuners->powersave_bias ?
 159                         CPUFREQ_RELATION_L : CPUFREQ_RELATION_H);
 160 }
 161
 162 /*
 163  * Every sampling_rate, we check, if current idle time is less than 20%
 164  * (default), then we try to increase frequency. Every sampling_rate, we look
 165  * for the lowest frequency which can sustain the load while keeping idle time
 166  * over 30%. If such a frequency exist, we try to decrease to this frequency.
 167  *
 168  * Any frequency increase takes it to the maximum frequency. Frequency reduction
 169  * happens at minimum steps of 5% (default) of current frequency
 170  */
 171 static void od_check_cpu(int cpu, unsigned int load_freq)
 172 {
 173         struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info, cpu);
 174         struct cpufreq_policy *policy = dbs_info->cdbs.cur_policy;
 175         struct dbs_data *dbs_data = policy->governor_data;
 176         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 177
 178         dbs_info->freq_lo = 0;
 179
 180         /* Check for frequency increase */
 181         if (load_freq > od_tuners->up_threshold * policy->cur) {
 182                 /* If switching to max speed, apply sampling_down_factor */
 183                 if (policy->cur < policy->max)
 184                         dbs_info->rate_mult =
 185                                 od_tuners->sampling_down_factor;
 186                 dbs_freq_increase(policy, policy->max);
 187                 return;
 188         }
 189
 190         /* Check for frequency decrease */
 191         /* if we cannot reduce the frequency anymore, break out early */
 192         if (policy->cur == policy->min)
 193                 return;
 194
 195         /*
 196          * The optimal frequency is the frequency that is the lowest that can
 197          * support the current CPU usage without triggering the up policy. To be
 198          * safe, we focus 10 points under the threshold.
 199          */
 200         if (load_freq < od_tuners->adj_up_threshold
 201                         * policy->cur) {
 202                 unsigned int freq_next;
 203                 freq_next = load_freq / od_tuners->adj_up_threshold;
 204
 205                 /* No longer fully busy, reset rate_mult */
 206                 dbs_info->rate_mult = 1;
 207
 208                 if (freq_next < policy->min)
 209                         freq_next = policy->min;
 210
 211                 if (!od_tuners->powersave_bias) {
 212                         __cpufreq_driver_target(policy, freq_next,
 213                                         CPUFREQ_RELATION_L);
 214                         return;
 215                 }
 216
 217                 freq_next = od_ops.powersave_bias_target(policy, freq_next,
 218                                         CPUFREQ_RELATION_L);
 219                 __cpufreq_driver_target(policy, freq_next, CPUFREQ_RELATION_L);
 220         }
 221 }
 222
 223 static void od_dbs_timer(struct work_struct *work)
 224 {
 225         struct od_cpu_dbs_info_s *dbs_info =
 226                 container_of(work, struct od_cpu_dbs_info_s, cdbs.work.work);
 227         unsigned int cpu = dbs_info->cdbs.cur_policy->cpu;
 228         struct od_cpu_dbs_info_s *core_dbs_info = &per_cpu(od_cpu_dbs_info,
 229                         cpu);
 230         struct dbs_data *dbs_data = dbs_info->cdbs.cur_policy->governor_data;
 231         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 232         int delay = 0, sample_type = core_dbs_info->sample_type;
 233         bool modify_all = true;
 234
 235         mutex_lock(&core_dbs_info->cdbs.timer_mutex);
 236         if (!need_load_eval(&core_dbs_info->cdbs, od_tuners->sampling_rate)) {
 237                 modify_all = false;
 238                 goto max_delay;
 239         }
 240
 241         /* Common NORMAL_SAMPLE setup */
 242         core_dbs_info->sample_type = OD_NORMAL_SAMPLE;
 243         if (sample_type == OD_SUB_SAMPLE) {
 244                 delay = core_dbs_info->freq_lo_jiffies;
 245                 __cpufreq_driver_target(core_dbs_info->cdbs.cur_policy,
 246                                 core_dbs_info->freq_lo, CPUFREQ_RELATION_H);
 247         } else {
 248                 dbs_check_cpu(dbs_data, cpu);
 249                 if (core_dbs_info->freq_lo) {
 250                         /* Setup timer for SUB_SAMPLE */
 251                         core_dbs_info->sample_type = OD_SUB_SAMPLE;
 252                         delay = core_dbs_info->freq_hi_jiffies;
 253                 }
 254         }
 255
 256 max_delay:
 257         if (!delay)
 258                 delay = delay_for_sampling_rate(od_tuners->sampling_rate
 259                                 * core_dbs_info->rate_mult);
 260
 261         gov_queue_work(dbs_data, dbs_info->cdbs.cur_policy, delay, modify_all);
 262         mutex_unlock(&core_dbs_info->cdbs.timer_mutex);
 263 }
 264
 265 /************************** sysfs interface ************************/
 266 static struct common_dbs_data od_dbs_cdata;
 267
 268 /**
 269  * update_sampling_rate - update sampling rate effective immediately if needed.
 270  * @new_rate: new sampling rate
 271  *
 272  * If new rate is smaller than the old, simply updating
 273  * dbs_tuners_int.sampling_rate might not be appropriate. For example, if the
 274  * original sampling_rate was 1 second and the requested new sampling rate is 10
 275  * ms because the user needs immediate reaction from ondemand governor, but not
 276  * sure if higher frequency will be required or not, then, the governor may
 277  * change the sampling rate too late; up to 1 second later. Thus, if we are
 278  * reducing the sampling rate, we need to make the new value effective
 279  * immediately.
 280  */
 281 static void update_sampling_rate(struct dbs_data *dbs_data,
 282                 unsigned int new_rate)
 283 {
 284         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 285         int cpu;
 286
 287         od_tuners->sampling_rate = new_rate = max(new_rate,
 288                         dbs_data->min_sampling_rate);
 289
 290         for_each_online_cpu(cpu) {
 291                 struct cpufreq_policy *policy;
 292                 struct od_cpu_dbs_info_s *dbs_info;
 293                 unsigned long next_sampling, appointed_at;
 294
 295                 policy = cpufreq_cpu_get(cpu);
 296                 if (!policy)
 297                         continue;
 298                 if (policy->governor != &cpufreq_gov_ondemand) {
 299                         cpufreq_cpu_put(policy);
 300                         continue;
 301                 }
 302                 dbs_info = &per_cpu(od_cpu_dbs_info, cpu);
 303                 cpufreq_cpu_put(policy);
 304
 305                 mutex_lock(&dbs_info->cdbs.timer_mutex);
 306
 307                 if (!delayed_work_pending(&dbs_info->cdbs.work)) {
 308                         mutex_unlock(&dbs_info->cdbs.timer_mutex);
 309                         continue;
 310                 }
 311
 312                 next_sampling = jiffies + usecs_to_jiffies(new_rate);
 313                 appointed_at = dbs_info->cdbs.work.timer.expires;
 314
 315                 if (time_before(next_sampling, appointed_at)) {
 316
 317                         mutex_unlock(&dbs_info->cdbs.timer_mutex);
 318                         cancel_delayed_work_sync(&dbs_info->cdbs.work);
 319                         mutex_lock(&dbs_info->cdbs.timer_mutex);
 320
 321                         gov_queue_work(dbs_data, dbs_info->cdbs.cur_policy,
 322                                         usecs_to_jiffies(new_rate), true);
 323
 324                 }
 325                 mutex_unlock(&dbs_info->cdbs.timer_mutex);
 326         }
 327 }
 328
 329 static ssize_t store_sampling_rate(struct dbs_data *dbs_data, const char *buf,
 330                 size_t count)
 331 {
 332         unsigned int input;
 333         int ret;
 334         ret = sscanf(buf, "%u", &input);
 335         if (ret != 1)
 336                 return -EINVAL;
 337
 338         update_sampling_rate(dbs_data, input);
 339         return count;
 340 }
 341
 342 static ssize_t store_io_is_busy(struct dbs_data *dbs_data, const char *buf,
 343                 size_t count)
 344 {
 345         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 346         unsigned int input;
 347         int ret;
 348         unsigned int j;
 349
 350         ret = sscanf(buf, "%u", &input);
 351         if (ret != 1)
 352                 return -EINVAL;
 353         od_tuners->io_is_busy = !!input;
 354
 355         /* we need to re-evaluate prev_cpu_idle */
 356         for_each_online_cpu(j) {
 357                 struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info,
 358                                                                         j);
 359                 dbs_info->cdbs.prev_cpu_idle = get_cpu_idle_time(j,
 360                         &dbs_info->cdbs.prev_cpu_wall, od_tuners->io_is_busy);
 361         }
 362         return count;
 363 }
 364
 365 static ssize_t store_up_threshold(struct dbs_data *dbs_data, const char *buf,
 366                 size_t count)
 367 {
 368         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 369         unsigned int input;
 370         int ret;
 371         ret = sscanf(buf, "%u", &input);
 372
 373         if (ret != 1 || input > MAX_FREQUENCY_UP_THRESHOLD ||
 374                         input < MIN_FREQUENCY_UP_THRESHOLD) {
 375                 return -EINVAL;
 376         }
 377         /* Calculate the new adj_up_threshold */
 378         od_tuners->adj_up_threshold += input;
 379         od_tuners->adj_up_threshold -= od_tuners->up_threshold;
 380
 381         od_tuners->up_threshold = input;
 382         return count;
 383 }
 384
 385 static ssize_t store_sampling_down_factor(struct dbs_data *dbs_data,
 386                 const char *buf, size_t count)
 387 {
 388         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 389         unsigned int input, j;
 390         int ret;
 391         ret = sscanf(buf, "%u", &input);
 392
 393         if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
 394                 return -EINVAL;
 395         od_tuners->sampling_down_factor = input;
 396
 397         /* Reset down sampling multiplier in case it was active */
 398         for_each_online_cpu(j) {
 399                 struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info,
 400                                 j);
 401                 dbs_info->rate_mult = 1;
 402         }
 403         return count;
 404 }
 405
 406 static ssize_t store_ignore_nice(struct dbs_data *dbs_data, const char *buf,
 407                 size_t count)
 408 {
 409         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 410         unsigned int input;
 411         int ret;
 412
 413         unsigned int j;
 414
 415         ret = sscanf(buf, "%u", &input);
 416         if (ret != 1)
 417                 return -EINVAL;
 418
 419         if (input > 1)
 420                 input = 1;
 421
 422         if (input == od_tuners->ignore_nice) { /* nothing to do */
 423                 return count;
 424         }
 425         od_tuners->ignore_nice = input;
 426
 427         /* we need to re-evaluate prev_cpu_idle */
 428         for_each_online_cpu(j) {
 429                 struct od_cpu_dbs_info_s *dbs_info;
 430                 dbs_info = &per_cpu(od_cpu_dbs_info, j);
 431                 dbs_info->cdbs.prev_cpu_idle = get_cpu_idle_time(j,
 432                         &dbs_info->cdbs.prev_cpu_wall, od_tuners->io_is_busy);
 433                 if (od_tuners->ignore_nice)
 434                         dbs_info->cdbs.prev_cpu_nice =
 435                                 kcpustat_cpu(j).cpustat[CPUTIME_NICE];
 436
 437         }
 438         return count;
 439 }
 440
 441 static ssize_t store_powersave_bias(struct dbs_data *dbs_data, const char *buf,
 442                 size_t count)
 443 {
 444         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 445         unsigned int input;
 446         int ret;
 447         ret = sscanf(buf, "%u", &input);
 448
 449         if (ret != 1)
 450                 return -EINVAL;
 451
 452         if (input > 1000)
 453                 input = 1000;
 454
 455         od_tuners->powersave_bias = input;
 456         ondemand_powersave_bias_init();
 457         return count;
 458 }
 459
 460 show_store_one(od, sampling_rate);
 461 show_store_one(od, io_is_busy);
 462 show_store_one(od, up_threshold);
 463 show_store_one(od, sampling_down_factor);
 464 show_store_one(od, ignore_nice);
 465 show_store_one(od, powersave_bias);
 466 declare_show_sampling_rate_min(od);
 467
 468 gov_sys_pol_attr_rw(sampling_rate);
 469 gov_sys_pol_attr_rw(io_is_busy);
 470 gov_sys_pol_attr_rw(up_threshold);
 471 gov_sys_pol_attr_rw(sampling_down_factor);
 472 gov_sys_pol_attr_rw(ignore_nice);
 473 gov_sys_pol_attr_rw(powersave_bias);
 474 gov_sys_pol_attr_ro(sampling_rate_min);
 475
 476 static struct attribute *dbs_attributes_gov_sys[] = {
 477         &sampling_rate_min_gov_sys.attr,
 478         &sampling_rate_gov_sys.attr,
 479         &up_threshold_gov_sys.attr,
 480         &sampling_down_factor_gov_sys.attr,
 481         &ignore_nice_gov_sys.attr,
 482         &powersave_bias_gov_sys.attr,
 483         &io_is_busy_gov_sys.attr,
 484         NULL
 485 };
 486
 487 static struct attribute_group od_attr_group_gov_sys = {
 488         .attrs = dbs_attributes_gov_sys,
 489         .name = "ondemand",
 490 };
 491
 492 static struct attribute *dbs_attributes_gov_pol[] = {
 493         &sampling_rate_min_gov_pol.attr,
 494         &sampling_rate_gov_pol.attr,
 495         &up_threshold_gov_pol.attr,
 496         &sampling_down_factor_gov_pol.attr,
 497         &ignore_nice_gov_pol.attr,
 498         &powersave_bias_gov_pol.attr,
 499         &io_is_busy_gov_pol.attr,
 500         NULL
 501 };
 502
 503 static struct attribute_group od_attr_group_gov_pol = {
 504         .attrs = dbs_attributes_gov_pol,
 505         .name = "ondemand",
 506 };
 507
 508 /************************** sysfs end ************************/
 509
 510 static int od_init(struct dbs_data *dbs_data)
 511 {
 512         struct od_dbs_tuners *tuners;
 513         u64 idle_time;
 514         int cpu;
 515
 516         tuners = kzalloc(sizeof(struct od_dbs_tuners), GFP_KERNEL);
 517         if (!tuners) {
 518                 pr_err("%s: kzalloc failed\n", __func__);
 519                 return -ENOMEM;
 520         }
 521
 522         cpu = get_cpu();
 523         idle_time = get_cpu_idle_time_us(cpu, NULL);
 524         put_cpu();
 525         if (idle_time != -1ULL) {
 526                 /* Idle micro accounting is supported. Use finer thresholds */
 527                 tuners->up_threshold = MICRO_FREQUENCY_UP_THRESHOLD;
 528                 tuners->adj_up_threshold = MICRO_FREQUENCY_UP_THRESHOLD -
 529                         MICRO_FREQUENCY_DOWN_DIFFERENTIAL;
 530                 /*
 531                  * In nohz/micro accounting case we set the minimum frequency
 532                  * not depending on HZ, but fixed (very low). The deferred
 533                  * timer might skip some samples if idle/sleeping as needed.
 534                 */
 535                 dbs_data->min_sampling_rate = MICRO_FREQUENCY_MIN_SAMPLE_RATE;
 536         } else {
 537                 tuners->up_threshold = DEF_FREQUENCY_UP_THRESHOLD;
 538                 tuners->adj_up_threshold = DEF_FREQUENCY_UP_THRESHOLD -
 539                         DEF_FREQUENCY_DOWN_DIFFERENTIAL;
 540
 541                 /* For correct statistics, we need 10 ticks for each measure */
 542                 dbs_data->min_sampling_rate = MIN_SAMPLING_RATE_RATIO *
 543                         jiffies_to_usecs(10);
 544         }
 545
 546         tuners->sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR;
 547         tuners->ignore_nice = 0;
 548         tuners->powersave_bias = default_powersave_bias;
 549         tuners->io_is_busy = should_io_be_busy();
 550
 551         dbs_data->tuners = tuners;
 552         mutex_init(&dbs_data->mutex);
 553         return 0;
 554 }
 555
 556 static void od_exit(struct dbs_data *dbs_data)
 557 {
 558         kfree(dbs_data->tuners);
 559 }
 560
 561 define_get_cpu_dbs_routines(od_cpu_dbs_info);
 562
 563 static struct od_ops od_ops = {
 564         .powersave_bias_init_cpu = ondemand_powersave_bias_init_cpu,
 565         .powersave_bias_target = generic_powersave_bias_target,
 566         .freq_increase = dbs_freq_increase,
 567 };
 568
 569 static struct common_dbs_data od_dbs_cdata = {
 570         .governor = GOV_ONDEMAND,
 571         .attr_group_gov_sys = &od_attr_group_gov_sys,
 572         .attr_group_gov_pol = &od_attr_group_gov_pol,
 573         .get_cpu_cdbs = get_cpu_cdbs,
 574         .get_cpu_dbs_info_s = get_cpu_dbs_info_s,
 575         .gov_dbs_timer = od_dbs_timer,
 576         .gov_check_cpu = od_check_cpu,
 577         .gov_ops = &od_ops,
 578         .init = od_init,
 579         .exit = od_exit,
 580 };
 581
 582 static void od_set_powersave_bias(unsigned int powersave_bias)
 583 {
 584         struct cpufreq_policy *policy;
 585         struct dbs_data *dbs_data;
 586         struct od_dbs_tuners *od_tuners;
 587         unsigned int cpu;
 588         cpumask_t done;
 589
 590         default_powersave_bias = powersave_bias;
 591         cpumask_clear(&done);
 592
 593         get_online_cpus();
 594         for_each_online_cpu(cpu) {
 595                 if (cpumask_test_cpu(cpu, &done))
 596                         continue;
 597
 598                 policy = per_cpu(od_cpu_dbs_info, cpu).cdbs.cur_policy;
 599                 if (!policy)
 600                         continue;
 601
 602                 cpumask_or(&done, &done, policy->cpus);
 603
 604                 if (policy->governor != &cpufreq_gov_ondemand)
 605                         continue;
 606
 607                 dbs_data = policy->governor_data;
 608                 od_tuners = dbs_data->tuners;
 609                 od_tuners->powersave_bias = default_powersave_bias;
 610         }
 611         put_online_cpus();
 612 }
 613
 614 void od_register_powersave_bias_handler(unsigned int (*f)
 615                 (struct cpufreq_policy *, unsigned int, unsigned int),
 616                 unsigned int powersave_bias)
 617 {
 618         od_ops.powersave_bias_target = f;
 619         od_set_powersave_bias(powersave_bias);
 620 }
 621 EXPORT_SYMBOL_GPL(od_register_powersave_bias_handler);
 622
 623 void od_unregister_powersave_bias_handler(void)
 624 {
 625         od_ops.powersave_bias_target = generic_powersave_bias_target;
 626         od_set_powersave_bias(0);
 627 }
 628 EXPORT_SYMBOL_GPL(od_unregister_powersave_bias_handler);
 629
 630 static int od_cpufreq_governor_dbs(struct cpufreq_policy *policy,
 631                 unsigned int event)
 632 {
 633         return cpufreq_governor_dbs(policy, &od_dbs_cdata, event);
 634 }
 635
 636 #ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND
 637 static
 638 #endif
 639 struct cpufreq_governor cpufreq_gov_ondemand = {
 640         .name                   = "ondemand",
 641         .governor               = od_cpufreq_governor_dbs,
 642         .max_transition_latency = TRANSITION_LATENCY_LIMIT,
 643         .owner                  = THIS_MODULE,
 644 };
 645
 646 static int __init cpufreq_gov_dbs_init(void)
 647 {
 648         return cpufreq_register_governor(&cpufreq_gov_ondemand);
 649 }
 650
 651 static void __exit cpufreq_gov_dbs_exit(void)
 652 {
 653         cpufreq_unregister_governor(&cpufreq_gov_ondemand);
 654 }
 655
 656 MODULE_AUTHOR("Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>");
 657 MODULE_AUTHOR("Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>");
 658 MODULE_DESCRIPTION("'cpufreq_ondemand' - A dynamic cpufreq governor for "
 659         "Low Latency Frequency Transition capable processors");
 660 MODULE_LICENSE("GPL");
 661
 662 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND
 663 fs_initcall(cpufreq_gov_dbs_init);
 664 #else
 665 module_init(cpufreq_gov_dbs_init);
 666 #endif
 667 module_exit(cpufreq_gov_dbs_exit);